The nuchal organ is a ciliated pit[1] or groove present at the posterior end of the prostomium of annelid worms,[1] some cephalopods,[2] and other invertebrates.[3]
Annelids only possess one nuchal organ, although the nature of the grooving may make it appear to be a pair of organs.[4]
It may be involved in light detection,[2] and may have a role in food detection and mating.[5]
Cephalopod anatomy | ||||||||||||||
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Shell |
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Mantle & funnel |
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Head & limbs |
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General |
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Developmental stages: Spawn → Paralarva (Doratopsis stage) → Juvenile → Subadult → Adult • Egg fossils • Protoconch (embryonic shell) |